Through which London district does the prime meridian pass?

The prime meridian passes through Greenwich, a district of southeast London. The historic line is marked at the Royal Observatory Greenwich, where visitors can stand across 0° longitude.

Greenwich became the internationally accepted reference point for longitude after the 1884 International Meridian Conference in Washington, D.C. Delegates selected the meridian running through the observatory’s transit instrument as the world’s zero-longitude reference. Longitudes are measured east or west from that line up to 180°.

A common mix-up is confusing the prime meridian with the International Date Line. Greenwich supplies the starting reference for measuring longitude, while the date line lies roughly opposite it on the 180th meridian. Modern satellite-based geodesy uses the International Reference Meridian, which differs slightly from the historic observatory line, but Greenwich remains the familiar cultural and educational reference.